Field of the Invention
The present invention relates to a marker apparatus for a display utilizing a reflection light beam and a light source light beam, which is particularly constructed mainly by a retroreflector.
A conventional marker apparatus for traffics utilizing a retroreflector has been proposed. A reflector constituted by a trigonal pyramid a vertical angle of which is a right angle or a reflective member constituted by a prism reflects, as well known, incident light beam toward 180.degree. opposite direction. Therefore, if they are practiced as a traffic marker and disposed on a road boundary such as a shoulder of the road, they reflect light beam emitting from an automotive headlamp back to a driver of the vehicle, so that the vehicle driver can recognize the road boundary and, thus, they can contribute to the safety drive. The marker of such a reflection type requires no power source as different from the other marker having a light source. However, because the reflection type marker negatively receives light beams to be reflected, the efficiency of recognition is limited especially in a case of a cloudy day in which surroundings are relatively dark but automotive headlamps are not turned on.
On the other hand, another marker apparatus employing a light source such as a bulb, an electronic flash or the like has been also proposed. This type of the marker apparatus positively emits light beam, and effective in respect of improving the recognition efficiency. However, if amount of light emitting from the light source is small, the recognition efficiency is also small, and it is difficult to achieve a desired performance. In contrast, if the light amount is large, the power consumption is increased and, accordingly, it is necessary to use the commercial power as a power source when used for a long time. In the latter case, electric codes must be connected to the marker lamp for supplying electric power, so that the marker apparatus must be large and bulky.
In view of the foregoing problems, there has been proposed still another type of marker apparatus in which both reflected light beam and light-source beams are employed. For example, Unexamined Japanese Utility Model Application No. Sho. 57-205185 discloses light emitting elements such as LEDs or the like serving as a light source, and light beam emitting from the light emitting elements are projected through a beam transmission plate. Further, a retroreflection lenses are arrayed at surroundings of the beam transmission plate, and light beam reflected by the retroreflection lenses are utilized for achieving the mark function. Thus, using both the reflected light beam and the light-source beam, the rate of load of the light emitting elements is decreased to thereby reduce the power consumption for the light emitting element, whereas, on the other hand, the recognition efficiency of the marker apparatus as a whole is enhanced by using owing to the mark functions of both the light emitting element and the retroreflection lenses.
However, since the Unexamined Japanese Utility Model Application No. Sho. 57-205185 merely uses both the light emitting element and the retroreflection lenses alone, each of the light emitting element and the retroreflection lenses independently functions as a marker. That is, no large involutional effect owing to an interaction of the both markers can be expected. Particularly, since the light emitting elements merely emit light to transmit through the beam transmission plate, although light distribution characteristics can be controlled by lens steps formed on the beam transmission plate, the beam condensibility or beam diffusibility is not freely adjusted, and the enhancement of the recognition efficiency is so limited. Further, since the retroreflection lenses are formed by fine lens steps, if an area of the lens is enlarged to enhance the recognition efficiency, the number of lens steps are also increased. Therefore, the production of the lens and also the production of a mold apparatus for producing the lens would be difficult.